1. Field of the Invention
This invention relates to a hearing aid intended to be mounted within an ear canal, comprising a microphone, an amplifier and an electromechanical transducer, for example, a telephone, accommodated in a housing, and including an extraction means for extracting the hearing aid from the ear canal, the input to the microphone being acoustically coupled to a sound entrance in the housing.
2. Description of the Related Art
Such a hearing aid is known from U.S. Pat. No. 4,756,312. A contact hearing aid is discussed there, in which the electromechanical transducer is in the form of a piezoelectric element generating vibrations which are transferred directly to the tympanic membrane. For this purpose, the hearing aid is to be mounted deep within the ear canal. It is more customary for the transducer to have the form of a telephone (loudspeaker) with which acoustic signals are generated which hit the tympanic membrane. In this embodiment too there are hearing aids which are to be mounted deep within the ear canal. For extracting such hearing aids from the ear canal, the hearing aids comprise extraction means.
The extraction means in the prior art hearing aid is in the form of a rod of ferromagnetic material which at one end cooperates with a magnet and the other end is capable of cooperating with a magnetic ring attached to the housing of the hearing aid. The magnet may be disposed in two positions relative to the rod. In one position of the magnet the hearing aid may be extracted from the ear canal by means of a magnetic force exerted on the ring of the hearing aid by the other end of the rod. In the other position of the magnet the rod can, prior to the hearing aid being extracted, be inserted into the ear canal without a force being exerted on the hearing aid by the rod. The prior-art hearing aid thus has the drawback of requiring a separate accessory for extracting the hearing aid. It is known to use, in lieu of a separate accessory, a component which is mechanically, hinged or not, coupled to the housing.